When a sheet or similar covering is placed on a mattress, it tends to slide because mattresses are commonly finished with a rather slippery surface. A flat sheet, mattress cover or even a fitted sheet slides because of the low friction between it and the mattress and, when a person gets into the bed, the sheet is likely to be displaced.
Various solutions have been proposed to solve this problem, including straps which extend beneath the mattress and engage marginal portions of the sheet. In principle, this is a sound solution, but its implementation has given rise to some problems which have not been adequately solved, particularly in the attachment between the ends of the strap and the sheet. It has been proposed, for example, to use a strap or belt which has snap members or similar fasteners at the ends and to then permanently attach mating snap members to the sheet itself. While this would seem to be workable, it has the disadvantages of requiring the purchaser to go through the process of attaching the snap fasteners to the sheets or else acquiring special sheets to accompany the strap, neither of which is a satisfactory solution.
Other devices of this type have used more universal attachment means not requiring special sheets, but the attachment devices have involved grippers which, in order to engage the sheet securely enough, tend to tear the fabric of the sheet, thereby shortening its useful life.
In addition, those strap devices proposed in the past have had limitations on their effectiveness and simplicity of installation because of the structural nature and the materials employed.